An elderly couple is sent to an alien civilian internment camp where one of them dies. Meanwhile, a German woman married to a prominent English magistrate has somehow avoided the camps but begins to feel the disdain of the community when a German bomb hits the centre of town.

A German attack is feared any day. Foyle investigates the sabotage and suspicious passing of Margaret Ellis who works for the White Feather hotel where a pro Hitler group meets every Friday. Foyle is surprised to learn that Sgt. Milner is a member of the Friday club.

It is June 1940 and a man dies in police cell after being refused exemption from joining the military by a Judge after being beaten by police. A young buy is evacuated from London and dies in an explosion at Judge Gascoigne's house when his garden office is blown up, this makes the police believe it was a revenge attack.

A man is found cuddled in the heart after a bomb raid on the city of Hastings. Foyle learns the dead man was a lorry driver who was moving valuable paintings to Wales for safety. Andrew, Foyle's son comes home on leave for an air-force base and his friend becomes the suspect of an investigation from special branch for being a communist sympathiser.